1. Field of the Invention
The present invention relates to a disc reproducing apparatus for reproducing an optical disc such as a CD-ROM or a DVD and a method for detecting its vibration.
2. Description of the Related Art
Recently, the speed-up (improvement of the reading speed of data) of disc drives for reproducing an optical disc such as a CD-ROM or a DVD is remarkable. By speeding up the disc drive, when a disc having a mass eccentricity (disc with its center of gravity deviated from the center of rotation) is reproduced by such a disc drive, the vibration generated in synchronization with the rotations of the disc becomes a prominent problem. This vibration is a factor to deteriorate the tracking performance of an optical pickup, resulting in lowering the data reading performance. The vibration and noise which leak out of the drive increase, and the use environment is remarkably degraded.
Conventionally, in order to suppress vibration generated when the disc having the mass eccentricity is reproduced, the vibration of the optical pickup and the like is directly detected by a sensor using an oscillator, and for example, a reproducing speed (transfer rate) is lowered if the vibration exceeding a predetermined value is detected.
But, such a method requires, in addition to a vibration sensor, many additional components such as a circuit for A/D conversion of the output from the vibration sensor to input a controller, causing a problem of increasing assembling man-hours and costs. Since a piezoelectric element type impact sensor is sensitive to surrounding electromagnetic noise, special consideration must be given to the mounting method and the use. In this connection, the cost is increased. In addition, these vibration sensors have a problem of having a detection error due to deviation or the like of parts.